Tech Area

Backfire Through Intake

Question: I have a problem with my 1988 2.5l 4 cyl. fiero. I have replaced my plugs and wires thinking my car was miss-firing but a friend told me that the engine was firing before the valves were closed. That is why it is back firing through the intake. You can baby it but when you get on it it back fires through the intake. I figured it is either the timing is off (how do I adjust that and to what setting?) or my crankshaft is worn. Can you please help me out?

Answer: There is no timing adjustments with the Direct Ignition System (DIS) that the 87-88 4 cyls use. Everything is done electronically by the computer.

Your problem will be the crankshaft sensor, the ignition module, one of the coils, or the ECM. It would be costly to just replace parts. In this case, paying a qualified technician to diagnois which is faulty will likely be less expensive.

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